Apparatus have been developed for opening envelopes by separating the edges of the opposing panels of an envelope by a variety of methods. Such methods include degradation of the envelope material along the envelope edges with heat or chemicals. Other methods include slitting the envelope edges with mechanical knife devices or otherwise separating the envelope panels by means of mechanical destruction of the envelope material.
After the opposing panels of an envelope have been separated from each other along one or more edges, the contents of the envelope must be removed or exposed for subsequent inspection and processing. A number of devices have been developed over the years for also removing or exposing the contents of envelopes.
The U.S. Pat. No. 3,590,548 discloses an envelope opener which weakens three edges of the envelope and includes a differential roller conveyor assembly comprising a conveyor belt and a roller with a brake which is selectively actuated in response to the appearance of the envelope in the opening mechanism to exert a shearing force on the envelope and lay back an edge thereof to expose the contents.
The U.S. Pat. No. 3,384,252 discloses an apparatus in which the top and bottom opposing panels of an envelope are engaged and moved apart by means of suction members. Mechanical clamping elements are then moved into the envelope to grip and remove the contents.
The U.S. Pat. No. 3,884,010 discloses an apparatus in which an envelope, severed along one edge, is gripped by means of a suction member and deposited horizontally in a compressive holder to bow both panels of the envelopes downwardly together. Subsequent upward movement of the suction member carries the engaged panel of the envelope away from the opposite panel to form a double bowed envelope. The envelope is then tilted 90 degrees to permit the contents to fall out of the double bowed envelope.
The U.S. Pat. Nos. 3,116,718 and 3,132,629 disclose various apparatus that use a suction member to lift the uppermost panel of an envelope that has been severed from the opposite panel along three edges. The uppermost panel is then folded back along the remaining unsevered edge that functions as an unfolding line. The contents of the envelope remain on the bottom, non-lifted panel. Movement of the envelope along a conveyor path causes the envelope to completely unfold to thereby expose the contents for extraction and removal.
The U.S. Pat. No. 3,888,069 discloses an apparatus in which an envelope is severed along three edges and moved forwardly between a pair of opposed conveying belts with the unsevered edge in the trailing position. The envelope is conveyed in this orientation beneath a friction roller which peels the top panel of the envelope to completely unfold the envelope and thereby expose the contents.
It would be desirable to provide a relatively simple method for exposing the contents of an envelope which has two opposing panels wherein the panels have been separated from each other along all but one straight edge portion where the panels remain connected. It would be desirable to provide such a method that could be effected with apparatus in which the need for complex mechanical envelope panel and/or contents gripping members is eliminated. Further, it would be desirable to provide a method which could be effected by apparatus in which the mechanical operations performed on the envelope and/or contents are reduced in number, if not eliminated altogether, so as to decrease the probability of the failure of the apparatus to effectively expose the contents of the envelope and so as to enable the apparatus to operate with a relatively high throughput rate.